When to plant basil in zone 9a

The zone 9a schedule for basil

Start seeds indoors

January 24 to February 7

Plant out

March 14 to 21

Sow outdoors

March 14 to 21

Soil warm enough (60°F), about

March 14

Safest planting date (10% frost risk)

March 25

First harvest, roughly

April 13 to 20

From the median frost dates of the NOAA stations assigned to the 1,736 ZIP codes in zone 9a, and the timing recommended by Cooperative Extension guides for basil.

Frost risk in zone 9a

Zones are based on winter cold, not on frost dates, so the last spring frost varies a lot within a zone. Across zone 9a, the typical last frost ranges from about February 13 in the earliest tenth of ZIP codes to March 21 in the latest tenth, and the first fall frost from November 14 to December 9. For a typical place in the zone:

• February 4Risky: a later frost happens in 9 years out of 10
• March 2Typical: frost after this date in half of years
• March 25Safe: a later frost only 1 year in 10

Basil are killed by frost, so if you want to be safe, plant out after the safe date rather than the typical one, or be ready to cover plants on a cold night.

Basil in zone 9a cities